Valve

ABSTRACT

A valve particularly adapted for use in controlling water and air delivered to a dental drill is the present subject matter. The valve generally consists of a valve body having a working air inlet for receiving working air and a working air outlet, which is connected to a dental drill. A working air valve controls the flow of working air to the working valve outlet. A working air valve operator is mounted in the body and is connected to the working air valve for controlling the flow of working air. A first control air passage is connected to the working air valve operator for conducting control air to the working air valve operator. A control air relief port and a control air valve are connected to the first control air passage for selectively determining the pressure in the control air passage for effecting the operation of the working air valve operator. A control air valve operator is connected to the control air valve for selectively positioning the control air valve to effect opening and closing of the working air valve. The body also has a water inlet passage and a water outlet passage, with a water valve controlling the flow of water into the water outlet passage. A water valve operator is connected to the water valve for selectively operating the water valve. A second control air passage is connected to the water valve operator. A second control air relief port is connected to the water valve operator, with a second air control valve controlling the flow of air out of the water valve operator into the second control air relief port to effect the operation of the water valve operator. A third control air passage is connected to the working air inlet. The third control air passage is connected to a third control air valve operator, which is connected to the second control air valve operator.

United States Patent [191 Miller 1 1 VALVE [76] Inventor: Timothy J. Miller, 1500 Lincoln St..

Evanston, 111. 60201 [22] Filed: Oct. 30. 1973 21 Appl. No.: 411,057

Primary Examiner-Robert G. Nilson Anorncy, Agent. or FirmAnthony S. Zummcr [57] ABSTRACT A valve particularly adapted for use in controlling water and air delivered to a dental drill is the present subject matter. The valve generally consists of a valve body having a working air inlet for receiving working air and a working air outlet, which is connected to a dental drill. A working air valve controls the flow of working air to the working valve outlet. A working air A] Elva 1 Apr. 8, 1975 valve operator is mounted in the body and is connected to the working air valve for controlling the flow of working air. A first control air passage is connected to the working air valve operator for conducting control air to the working air valve operator. A control air relief port and a control air valve are connected to the first control air passage for selectively determining the pressure in the control air passage for effecting the operation of the working air valve operator. A control air valve operator is connected to the control air valve for selectively positioning the control air valve to effect opening and closing of the working air valve. The body also has a water inlet passage and a water outlet passage, with a water valve controlling the flow of water into the water outlet passage. A water valve operator is connected to the water valve for selectively operating the water valve. A second control air passage is connected to the water valve operator. A second control air relief port is connected to the water valve operator, with a second air control valve controlling the flow of air out of the water valve operator into the second control air relief port to effect the operation of the water valve operator. A third control air passage is connected to the working air inlet. The third control air passage is connected to a third control air valve operator, which is connected to the second control air valve operator.

10 Claims, 5 Drawing Figures PATENTEUAPR 81975 PATENTEDAPR 8197s swan z or 3 lZZ VALVE BACKGROUND OF THE INVENTION The present invention relates to an improved valve construction, which is particularly adapted for use in controlling dental drills of the type which are driven by compressed air.

The high-speed dental drill which is used by many dentists today is one which utilizes a drill having an air turbine as the motor for driving the drill. The air turbine is driven by compressed air to drive a burr on the end of a dental drill at a very high speed. It is generally well-recognized that part of the discomfort which is caused by drilling of a tooth is caused by the heat generated in the drilling operation. Most of the air-driven. high-speed drills also have a source of cooling water delivered to the burr. Dentists generally find that. though the cooling water acts as a coolant to the tooth, it does sometimes obscure the view that the dentist has. so that many dentists find that they prefer to have selectivity as to whether cooling water is to be delivered to the burr or not.

In the normal drilling of a tooth. a dentist may use a number of burrs. In view of the fact that the dentist finds that he spends a considerable amount of time in changing burrs during a drilling operation, he prefers to have two or more hand pieces available in the drilling operation. However. he also finds that he prefers to use only one set of foot pedals, which control the operation of the drill. The disengagement and recngagement of a dental drill is even more cumbersome than changing burrs. so that most dentists continue to use a single drill hand piece and change the burrs as needed.

The present invention provides a valve which may be used with a dentists high-speed drilling equipment. which is so connected that the dentist may have two or more drills controlled by a single set of foot pedals. Only the drill which he is holding is the active drill: and the drills which are not in use. but are stored, are locked out of operation.

SUMMARY OF THE INVENTION The present invention provides an improved construction for use in a dental drill arrangement wherein two or more of the valves are mounted in cooperative association to receive compressed air and water, and deliver compressed air and water only to a single drill. so that a dentist may use a single set of foot-pedaloperated valves for control of a selected hand drill.

The specific construction of the valve is such that the valve allows water to flow to the selected drill only when there is compressed air available. The valve includes an improved construction wherein interruption of the water supply to the drill causes the valve to have an automatic retraction of water back into the valve to eliminate the dripping of water onto the burr after the flow of water has been interrupted.

The present valve construction is such that it provides an integral unit. which may be easily removed and exchanged for another unit in order to service the unit.

Other objects and uses of the present invention will become readily apparent to those skilled in the art upon a perusal of the following specification in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a partial schematic view, showing a pair of valves embodying the herein-disclosed invention mounted in an abutting relationship, with a conventional foot pedal shown connected to the valves and to conventional air-driven, high-speed dental drills;

FIG. 2 is a side elevational view of one of the valves and associated equipment shown in FIG. 1;

FIG. 3 is an end elevational view of the valve shown in FIG. 2;

FIG. 4 is a cross-sectional view through the valve shown in FIG. 2, taken on Line 4-4 showing the specific construction of the valve and a portion of a valve manifold shown in partial cross-sectional view; and

FIG. 5 is a cross-sectional view through the valve shown in FIG. 2, taken on Line 5-5 taken in the opposite direction to that of FIG. 4, also showing the manifold in partial cross-sectional view.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings. and especially to FIG. 1, a general view of a dental drill control assembly is shown therein, with a pair of high-speed dental drills I0 and 12 shown connected to valves 14 and 16, respectively. The dental drills are controlled by conventional foot-pedal-operated valve assembly 18. The valve 14 is connected to a manifold 20; and the valve 16 is connected to a manifold 22. The two manifolds 20 and 22 are interconnected. The manifold 20 is connected to a water input line 24, which is only shown schematically herein. A compressed air input line 26 is also connected to a manifold 20. The manifolds 20 and 22, with the valves 14 and 16 mounted thereon. are mounted on a conventional support bar 28.

Looking now to FIG. 2, it may be seen that the dental drill 10 is of conventional construction and is connected to the valve 14 through conventional flexible hoses 30 and 32, which are connected to the manifold 20 in a conventional and well-known manner.

The drill 10 is supported in a conventional holder 34, which is mounted on a drill holder assembly 36. The drill holder assembly 36 includes a pair of side bars 38 and 40, which are fixed to the valve 14. A pivot pin 42 extends through the side bars 38 and 40, and pivotedly supports a center bar 44, which has the holder 34 mounted thereon. The center bar 44 has a latch 46 pivotedly mounted on its back. so that the center bar may be locked into a position substantially parallel to the side bars 38 and 40, for reasons which will become apparent hereinafter.

Looking now to FIGS. 4 and 5, the details of construction of the valve 14 and the manifold 20 may be seen therein. As was mentioned above. the manifold 20 is connected to water line 24 and compressed air line 26. The water line 24 is connected to a conventional source of water under pressure. while the compressed air line is connected to a source of compressed air under pressure. Neither of these sources is shown inasmuch as they are quite conventional in the art.

The inner construction of the manifold 20 is not shown in detail herein inasmuch as construction of a manifold having a plurality of openings is well-known in the art; and one skilled in the art would have no trouble in building a manifold to provide the necessary functions. The manifold 20 has a water line 48 extending therethrough, with a branch extehding toward the valve 14. The manifold also has a working air line 52 extending through the manifold and has a branch 54 extending toward the valve 14. The manifold also has a working air outlet passage 56, which is connected to the hose 30. In addition, the manifold has a water outlet passage 58, which connects to hose 32. As was mentioned above, the hoses 30 and 32 are connected to the drill 10 in a conventional manner.

The compressed air line 26 is connected to a compressed air line through appropriate manifold porting; and the air line 60 is connected to the pedal control 18. The air delivered through line 60 is divided into three parts in the pedal control assembly 18, with a pedal 62 controlling valves to working air line 64 and first control air line 66, while pedal 68 controls a valve to second control air line 70. The air lines 64, 66 and 70 are returned back to the manifold, where the line 64 is connected to the working air line 52 through appropriate manifold porting to control the flow of air into branch 54. The control line 66 is connected to a control lead 72 through appropriate manifold porting. The control lead 72 extends through the manifold and has a branch 74 connected thereto. The air line 70 is connected to a second control air lead 76 having a branch 78 extending toward the valve 14.

As was mentioned above, the valve 14 is connected to the manifold 20. The valve 14 has a valve body 80, with a plurality of valves and valve operators contained in the body. The valve body 80 has a manifold face 82, which contains a plurality of apertures which align with apertures in the manifold to allow fluids to pass from the manifold into the valve body and either back into the manifold or out of the valve body.

The valve face 82 has a working air inlet 84 in its center portion aligned with the branch 54 for receipt of working air from the manifold. The air inlet is connected to a working air chamber 86, which has a working air valve 88 mounted therein. A working air outlet 87 opens into working air chamber 86 and is aligned with the working air outlet passage 56. The working air valve 88 is conventional in its construction and has a stem 90, with a platform 92 formed integral with the stem. Formed integral with the outer periphery of the platform 92 there is a torus 94, which provides a sealing surface. The chabmer 86 has an outlet 96 with the stem positioned therein. The outlet 96 is connected to a relief chamber 98. A working air relief port 100 in the valve body opens into the relief chamber 98 to provide communication with atmosphere. A disk 102 is positioned in the relief chamber and is engageable with the stem 90.

A working air valve operator 104 is positioned in the body 80 and is connected to the working air valve 88. The working air valve operator 104 includes a rubber diaphragm 106 which is distendible and is engageable with disk 102 for selectively holding valve 88 in a closed attitude. The operator includes an operator chamber 108 of which diaphragm 106 is one side thereof. The chamber 108 has a port 110 opening therein, which port 110 is connected to a first control air passage 112. The working air valve operator also has a disk 114 mounted therein.

The aforementioned first control air passage 112 is connected to an aperture 116 in the valve face 82. A restrictor 118 is positioned in the aperture 116 to keep the flow of air through the passage at a minimum, for

reasons which will become apparent hereinafter. The passage 112 extends substantially the entire length of the valve body, and has an opening 120 into a first control air chamber 122. The chamber 122 has a control air flow port 124 in one side to allow the first control air to flow into a first control air relief chamber 126. A control air relief port 128 is in the valve body to allow the chamber to vent to atmosphere. A valve disk 130 is positioned in the chamber 126, and has a spring 132 connected thereto, urging the disk 130 away from the port 124. When the disk 130 is moved to cover the port. the port is closed to prevent air from flowing out of chamber 122, through port 124, and into chamber 126. The disk 130 is a control air valve determining the flow of control air from the opening 120 to the port A control air valve operator 134 is connected to the control air valve to close the port 124 selectively. The control valve operator 134 includes a chamber 136, which has a rubber diaphragm 138 forming one side thereof. The other side of the chamber 136 includes a valve outer wall 140, which has a stem aperture 142 formed therein. A stem disk 144 is positioned in the aperture 136 and is engageable with the diaphragm 138. A stem 146 extends through the stem aperture 142 beyond the outer wall 140. The stem 146 includes a flange 148, which keeps the stem in the aperture and provides an enlarged surface for engagement with the stern disk 144.

It may be appreciated that, as air is forced through passage 112, the air enters chamber 122, flows through port 124, and into chamber 126. The air flows out of the relief port 128, so that the air in passage 112 is at a relatively low pressure. However, when an inward force is applied to stem 146 to force stem into chamber 136, the diaphragm 138 is distended to move disk 130 toward port 124 to close port 124. The closing of the port 124 allows the air pressure in the working air valve operator 104 to build up to distend the diaphragm 106, thereby pushing the disk 102 against valve 88 to close the inlet aperture 84.

Water is delivered to valve 14 from the wter line 24, along line 48, to branch 50, and to a water passage 150 in the valve body. The water passage 150 is connected to a water chamber inlet 152 to provide a water flow path into a water chamber 154. The water chamber 154 has a water valve aperture 156 in one side thereof to allow water to flow into a water outlet chamber 158. The watear outlet chamber has a water outlet 160, which water outlet is connected to a water outlet passage 162. The water outlet passage 162 connects with the water outlet passage 58, which is in turn connected to the dental drill 10 by hose 32. A water valve 164 is mounted in water chamber 154 for selectively closing water valve aperture 156. The water valve includes a stem 166 positioned in aperture 156 and a flange 168 formed integral with the stem. A torus 170 is formed integral with the outer periphery of the flange 168 for engagement with a wall of the chamber 154 to form a seal therewith. The valve 164 is held in a normally closed attitude by a spring 172, which holds a platform 174 against the bottom of the torus 170. A water valve disk 176 is positioned in the water outlet chamber 158 in engagement with the stem 166. A spring 177 is posi tioned in chamber 158 in engagement with disc 176, urging the disc away from stem 166.

A water valve operator 178 is connected to the water valve 164 through the disk 176. The water valve operator includes an expandible chamber 180 having a water valve operator disk 182 positioned therein. The expandible chamber 180 has a passage 184 in one side thereof. The passage 184 opens into a second control air relief chamber 186. The valve body 80 has a second control air relief port 188 opening into the chamber 186 to allow air from the chamber to exhaust into atmosphere. A disk 190 positioned in chamber 186, with a spring 192 constantly urging the disk away from the passage 184, is a second control air valve controlling the flow of air from the chamber 180 into the second control air relief port.

A second control air passage 194 extends axially along the valve body. and has a second control air inlet 196 opening into the chamber 180. Second control air thus flows along passage 194, through inlet 196, through chamber 180, through passage 184, into chamber 186 and out port 188, unless disk 190 closes the passage 184. A restrictor 197 is positioned in passage 194 adjacent to valve face 88 to reduce air loss through port 188 when disc 190 is positioned away from passage 184. When passage 184 is closed, the air under pressure builds up sufficient pressure to distend a rubber diaphragm 200, which forms one side of chamber 180. The diaphragm engages the disk 176 to move the water valve 164 away from the aperture 156 to allow water to flow from chamber 154 to chamber 158.

A third control air valve operator 202 is connected to the second control air valve. A third control air passage 204, which is parallel to second control air passage 194, has a third control air opening 206 in the working air chamber 86 and an opening 208 into an expandible chamber 210, which is part of the third control air valve operator. A disk 212 is positioned in the chamber 210. A rubber diaphragm 214 forms an extendible side of the chamber 210.

In operation, the dentist selects either one of the drills or 12 for use. For purposes of illustration, the operation of valve 14 in cooperation with drill 10 shall be discussed in detail. but it should be understood that operation of drill 12 with its respective valve 16 is the same. When the dentist lifts drill 10 and the force is relieved from stem 146, spring 132 pushes the disk 130 away from passage 124. The dentist uses his foot to manipulate pedal 62 to allow air to flow in lines 64 and 66 and provide working air in working air line 52 and first control air in control lead 72. The first control air flows along passage 112, into chamber 122, through passage 124, and exits through port 128 into the atmosphere. The working air under pressure enters the opening 84 to displace the valve 88. It may be appreciated that the force of the air pushes the valve upward and closes the opening 96. The working air then flows out of the working air passage 87, through the manifold, and into line 30, where the air flows into the drill 10 to drive an air motor.

As was mentioned above, the water valve 164 is in a normally closed attitude, so that, even though water is being provided into chamber 154, none is delivered to the drill. When the dentist wishes to apply water, he need only manipulate pedal 68 to provide second control air into passage 76 and into passage 194, where the second control air under pressure flows into the chamber 180. It may be appreciated that the working air also serves to expand chamber 210, so that diaphragm 214 is forced against the disk 190 to close the passage 184. Thus, the second control air causes air pressure to build up in chamber 180, thereby distending the diaphragm 200 against the disk 176 and displacing the water valve 164 to allow water to flow through aperture 156, into chamber 158, into opening 160, along passage 162, to be delivered to the line 32 and then to drill 10. It should be appreciated that no water will be allowed to flow through aperture 156 unless there is sufficient working air pressure to distend diaphragm 214 to close passage 184. Thus, it is impossible to have water delivered to the drill when there is no working air being delivered.

When the dentist wishes to stop the flow of water, he need only manipulate pedal 68 to interrupt the supply of the second control air into passage 194. This causes the elastic diaphragm 200 to retract to its original position and thereby allows valve 164 to close. It should further be noted that the quick return of spring 177 after the valve has been closed causes a negative pressure to be built up in the chamber 158, so that some of the water in the water passage is sucked back up into the chamber, thereby not only causing an instantaneous stoppage of water but preventing the dripping of water during the use of the drill.

The valve automatically shuts off water and air to the drill when the drill is inserted in its carrier 34. The weight of the drill in the carrier causes the stem 146 to be pushed in, thereby distending the diaphragm 138, which forces the disk to block the passage 134. This causes the pressure to build up in passage 112, which in turn builds up the pressure in chamber 108. The build-up of air pressure in chamber 108 causes the diaphragm 106 to distend, thereby forcing the disk 102 into engagement with the working air valve 88 to close the opening 84. The air pressure in the working air chamber is relieved through the port 100. When the pressure in chamber 210 is relieved, the diaphragm 214 assumes a flat position, to release disk from its attitude of closing passage 184. Then, there is no flow of water or air into lines 30 and 32. Should the dentist wish to change a burr or otherwise service the drill, the valve may be locked into an inoperative position by forcing the center bar 44 against stem 146 and rotating latch 46 to lock the center bar into position.

As was mentioned above, the manifolds are mounted in tandem. The construction of manifold 22 is substantially identical to manifold 20; but manifold 22 does not have the connection to the source of water and compressed air. All of the water and compressed air to manifold 22 comes from manifold 20, which has its leads registering with like leads in manifold 22. Manifold 22 has the ends of its leads closed. The operation of the control air and other air is operative with the given drill, which is controlled by its respective valve from which the drill has been removed. It may be appreciated that, though only two drills have been shown with valves, a plurality of drills may be placed in lines. A dentist may have selected burrs on each of the drills for his normal operation. It is apparent that the dentist may control with his foot pedals the drill which he has removed from the respective valve so that he has only one control for a plurality of drills.

Although a specific embodiment has been shown and described herein, it is readily apparent that those skilled in the art may make various modifications and changes in the instant disclosure without departing from the spirit and scope of the present invention. It is to be expressly understood that the instant invention is limited only by the appended claims.

What is claimed is:

l. A valve for controlling fluids to be delivered to a dental drill comprising, a valve body, a working air inlet in said body adapted for receiving working air, a working air chamber in said valve body connected to the working valve inlet, a working air outlet in said valve body communicating with said working air chamber, a working air valve positioned in said working air chamber for controlling the flow of working air into the working air outlet, a working air valve operator in said valve body connected to said working air valve for moving the working air valve to control the flow of working air into the working air outlet, a first control air passage in said valve body connected to the working air valve operator for conducting first control air under pressure to the working air valve operator, a control air relief port connected to said first control air passage, a control air valve in said valve body for selectively controlling the flow of the first control air from said first control air passage into the control air relief port, a control air valve operator connected to said control air valve, a water inlet passage in said valve body, a water chamber connected to said water inlet passage for conducting water to said water chamber, a water outlet passage in said valve body and connected to the water chamber, a water valve in said chamber controlling the flow of water into the water outlet passage, a water valve operator in said valve body connected to the water valve for selectively operating the water valve to control the flow of water into the water outlet passage, a second control air passage in said body connected to said water valve operator for conducting second control air under pressure to the water valve operator. a second control air relief port connected to the water valve operator, a second control air valve in said body for selectively controlling the flow of second control air out of the water valve operator and into the second control air relief port, a third control air passage in the valve body connected to the working air chamber, and a second control air valve operator connected to the control air passage for receiving working air under pressure, and second control air valve operator connected to the second control air valve.

2. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein said water valve operator includes an elastic diaphragm extendible by air pressure to open the water valve and release of the air pressure returns the diaphragm to its normal position to close the water valve and create a negative pressure in the water outlet passage to pull water back into the water outlet passage.

3. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein the water valve is a normally closed valve and the water valve is opened by increasing the pressure of the second control air in the water valve operator.

4. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and flow of working air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chamber to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve.

5. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein said second control air valve is normally open to allow control air under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port, and closing of the normally open control air valve causes the second control air to build up air pressure in the water valve operator to move the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage.

6. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein the water valve is a normally closed valve, said water valve operator includes a diaphragm bieng extendible by air pressure to be connected to the water valve to open said water valve and release of air pressure from the diaphragm returns the diaphragm to its normal position to allow the water valve to close and to create a negative pressure in the water outlet passage to pull water back into the water outlet passage.

7. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein said second control air valve is normally open to allow air under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port, and closing of the normally open control air valve causes the air under pressure in the second control air passage to build up air pressure in the water valve operator, said water valve operator includes a diaphragm being extendible by air pressure and being connected to the water valve to move the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage, whereby opening of the water valve operator valve releases the air pressure on the extendible diaphragm to allow the water valve to close and to create a negative pressure in the water outlet passage to pull water back into the water outlet passage.

8. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and a flow of working air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chamber to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve, and wherein said water valve operator includes a diaphragm being extendible by air pressure to open the water valve and release of the air pressure returns the diaphragm to its normal position to close the water valve.

9. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and flow of air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chamber to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve. and wherein said second control air valve is normally open to allow air under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port. and closing of the normally open control air valve causes the air under pressure in the second control air passage to build up air pressure in the water valve operator to move the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage.

10. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and flow of air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chambar to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve, and wherein the water valve is a normally closed valve, said second control air valve is normally open to allow air LII under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port, and closing of the normally open control air valve causes the air under pressure in the second control air passage to build up, said water valve operator includes a diaphragm being extendible by air under pressure from the second air control passage, said diaphragm being connected to the water valve, whereby extension of the extendible diaphragm by air under pressure moves the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage and opening of the water valve operator valve causes release of the air under pressure against the diaphragm to close the water valve. 

1. A valve for controlling fluids to be delivered to a dental drill comprising, a valve body, a working air inlet in said body adapted for receiving working air, a working air chamber in said valve body connected to the working valve inlet, a working air outlet in said valve body communicating with said working air chamber, a working air valve positioned in said working air chamber for controlling the flow of working air into the working air outlet, a working air valve operator in said valve body connected to said working air valve for moving the working air valve to control the flow of working air into the working air outlet, a first control air passage in said valve body connected to the working air valve operator for conducting first control air under pressure to the working air valve operator, a control air relief port connected to said first control air passage, a control air valve in said valve body for selectively controlling the flow of the first control air from said first control air passage into the control air relief port, a control air valve operator connected to said control air valve, a water inlet passage in said valve body, a water chamber connected to said water inlet passage for conducting water to said water chamber, a water outlet passage in said valve body and connected to the water chamber, a water valve in said chamber controlling the flow of water into the water outlet passage, a water valve operator in said valve body connected to the water valve for selectively operating the water valve to control the flow of water into the water outlet passage, a second control air passage in said body connected to said water valve operator for conducting second control air under pressure to the water valve operator, a second control air relief port connected to the water valve operator, a second control air valve in said body for selectively controlling the flow of second control air out of the water valve operator and into the second control air relief port, a third control air passage in the valve body connected to the working air chamber, and a second control air valve operator connected to the control air passage for receiving working air under pressure, and second control air valve operator connected to the second control air valve.
 2. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein said water valve operator includes an elastic diaphragm extendible by air pressure to open the water valve and release of the air pressure returns the diaphragm to its normal position to close the water valve and create a negative pressure in the water outlet passage to pull water back into the water outlet passage.
 3. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein the water valve is a normally closed valve and the water valve is opened by increasing the pressure of the second control air in the water valve operator.
 4. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and flow of working air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chamber to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve.
 5. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein said second control air valve is normally open to allow control air under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port, and closing of the normally open control air valve causes the second control air to build up air pressure in the water valve operator to move the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage.
 6. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein the water valve is a normally closed valve, said water valve operator includes a diaphragm bieng extendible by air pressure to be connected to the water valve to open said water valve and release of air pressure from the diaphragm returns the diaphragm to its normal position to allow the water valve to close and to create a negative pressure in the water outlet passage to pull water back into the water outlet passage.
 7. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1 wherein said second control air valve is normally open to allow air under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port, and closing of the normally open control air valve causes the air under pressure in the second control air passage to build up air pressure in the water valve operator, said water valve operator includes a diaphragm being extendible by air pressure and being connected to the water valve to move the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage, whereby opening of the water valve operator valve releases the air pressure on the extendible diaphragm to allow the water valve to close and to create a negative pressure in the water outlet passage to pull water back into the water outlet passage.
 8. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and a flow of working air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chamber to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve, and wherein said water valve operator includes a diaphragm being extendible by air pressure to open the water valve and release of the air pressure returns the diaphragm to its normal position to close the water valve.
 9. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and flow of air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chamber to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve, and wherein said second control air valve is normally open to allow air under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port, and closing of the normally open control air valve causes the air under pressure in the second control air passage to build up air pressure in the water valve operator to move the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage.
 10. A valve for controlling fluids to be delivered to a dental drill as defined in claim 1, including a relief chamber connected to the working air chamber and flow of air between the relief chamber and the working air chamber is controlled by the working air valve, and a working air relief port connected to the relief chamber to allow working air to be expelled from the relief chamber and the working air chamber upon closing of the working air outlet by the working air valve, and wherein the water valve is a normally closed valve, said second control air valve is normally open to allow air under pressure from the second control air passage to flow out of the water valve operator to said second control air relief port, and closing of the normally open control air valve causes the air under pressure in the second control air passage to build up, said water valve operator includes a diaphragm being extendible by air under pressure from the second air control passage, said diaphragm being connected to the water valve, whereby extension of the extendible diaphragm by air under pressure moves the water valve into an attitude to allow water to pass from the water chamber into the water outlet passage and opening of the water valve operator valve causes release of the air under pressure against the diaphragm to close the water valve. 